Fail Of The Week: 3D Printed Worm Gear Drive Project Unveils Invisible Flaw

All of us would love to bring our projects to life while spending less money doing so. Sometimes our bargain hunting pays off, sometimes not. Many of us would just shrug at a failure and move on, but that is not [Mark Rehorst]’s style. He tried to build a Z-axis drive for his 3D printer around an inexpensive worm gear from AliExpress. This project was doomed by a gear flaw invisible to the human eye, but he documented the experience so we could all follow along.

We’ve featured [Mark]’s projects for his ever-evolving printer before, because we love reading his well-documented upgrade adventures. He’s not shy about exploring ideas that run against 3D printer conventions, from using belts to drive the Z-axis to moving print cooling fan off the print head (with followup). And lucky for us, he’s not shy about document his failures alongside the successes.

He walks us through the project, starting from initial motivation, moving on to parts selection, and describes how he designed his gearbox parts to work around weaknesses inherent to 3D printing. After the gearbox was installed, the resulting print came out flawed. Each of the regularly spaced print bulge can be directly correlated to a single turn of the worm gear making it the prime suspect. Then, to verify this observation more rigorously, Z-axis movement was measured with an indicator and plotted against desired movement. If the problem was caused by a piece of debris or surface damage, that would create a sharp bump in the plot. The sinusoidal plot tells us the problem is more fundamental than that.

This particular worm gear provided enough lifting power to move the print bed by multiplying motor torque, but it also multiplied flaws rendering it unsuitable for precisely positioning a 3D printer’s Z-axis. [Mark] plans to revisit the idea when he could find a source for better worm gears, and when he does we’ll certainly have the chance to read what happens.

Tricked-out Barbecue Will Make You Do A Spit Take

[Strn] and his friends love to barbecue no matter what it’s like outside. But something always seems to interrupt the fun: either it’s time to get up and turn the meat, or the music stops because somebody’s phone ran out of juice, or darkness falls and there aren’t enough flashlights or charged-up phones. He had the idea to build the Swiss Army knife of barbecues, a portable powerhouse that solves all of these problems and more (translated).

Most importantly, the E-Mangal rotates the skewers for even cooking. It does this with a 3D-printed worm gear system driven by the heater flap actuator from a car. After 25 minutes of slow rotation, a voice announces that it’s time to eat. [Strn] and friends will never hurt for music options between the pre-loaded tracks, Bluetooth audio, FM antenna, USB, and SD options running through a 3W amp. Two USB lights illuminate nighttime barbecuing, and the 10 Ah battery can do it all and keep everyone’s phone charged. For safety’s sake, [Strn] included a half-liter water tank to extinguish the coals via jet stream. Everything is run by a PIC18F, and it can be controlled at the box or through a simple web interface.

We love the look of this barbecue controller almost as much as the functionality. The sturdy stance of those short, angled legs give it a mid-century appliance feel, and seeing all the guts on display is always a plus. Grab a turkey leg and take the tour after the break.

The E-Mangal has a thermocouple in the coal box to measure the temperature, but there’s no direct control. If you’re more interested in temperature options than entertainment, here’s a project that micromanages everything on the grill.

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